In “…If One of Them is Dead”, Ava, Dylan and Caitlin (Sydney Park) kick their investigating into high gear when they identify a possible suspect in Nolan’s murder, while Alison (Sasha Pieterse) begins to look into the circumstances surrounding the mysterious suicide of Taylor Hotchkiss (Hayley Erin).

Seeing the Perfectionists juggle sleuthing with their intense academic demands, Alison decides to use her past in Rosewood as a way to mentor them through their current situation.